New Alfred [Powerpack] user here, with a first theme submission. Made these minimalist themes for personal use and decided to share them - Morning is my go-to. Names inspired by the Charles Spurgeon devotional, Morning and Evening. Enjoy.
Morning:
...download Morning by Codewyn
...import Morning by Codewyn:
alfred://theme/searchForegroundColor=rgba(65,65,65,1.00)&resultSubtextFontSize=0&searchSelectionForegroundColor=rgba(255,255,255,1.00)&separatorColor=rgba(255,255,255,0.00)&resultSelectedBackgroundColor=rgba(0,0,0,0.00)&shortcutColor=rgba(214,214,214,1.00)&scrollbarColor=rgba(213,213,213,1.00)&imageStyle=4&resultSubtextFont=Helvetica&background=rgba(255,255,255,1.00)&shortcutFontSize=1&searchFontSize=2&resultSubtextColor=rgba(214,214,214,1.00)&searchBackgroundColor=rgba(0,0,0,0.00)&name=Morning&resultTextFontSize=2&resultSelectedSubtextColor=rgba(95,95,95,1.00)&shortcutSelectedColor=rgba(0,0,0,1.00)&widthSize=3&border=rgba(0,0,0,0.50)&resultTextFont=Helvetica&resultTextColor=rgba(203,203,203,1.00)&cornerRoundness=3&searchFont=Helvetica&searchPaddingSize=0&credits=Codewyn&searchSelectionBackgroundColor=rgba(214,214,214,1.00)&resultSelectedTextColor=rgba(0,0,0,1.00)&resultPaddingSize=2&shortcutFont=Helvetica
Evening:
...download Evening by Codewyn
...import Evening by Codewyn:
alfred://theme/searchForegroundColor=rgba(191,191,191,1.00)&resultSubtextFontSize=0&searchSelectionForegroundColor=rgba(255,255,255,1.00)&separatorColor=rgba(255,255,255,0.00)&resultSelectedBackgroundColor=rgba(0,0,0,0.00)&shortcutColor=rgba(50,50,50,1.00)&scrollbarColor=rgba(94,94,94,1.00)&imageStyle=8&resultSubtextFont=Helvetica&background=rgba(0,0,0,1.00)&shortcutFontSize=1&searchFontSize=2&resultSubtextColor=rgba(52,52,52,1.00)&searchBackgroundColor=rgba(0,0,0,0.00)&name=Evening&resultTextFontSize=2&resultSelectedSubtextColor=rgba(80,80,80,1.00)&shortcutSelectedColor=rgba(255,255,255,1.00)&widthSize=3&border=rgba(255,255,255,0.20)&resultTextFont=Helvetica&resultTextColor=rgba(65,65,65,1.00)&cornerRoundness=3&searchFont=Helvetica&searchPaddingSize=0&credits=Codewyn&searchSelectionBackgroundColor=rgba(34,34,34,1.00)&resultSelectedTextColor=rgba(255,255,255,1.00)&resultPaddingSize=2&shortcutFont=Helvetica

There have been a few requests in response to The minimalist: Almost White v2 for a black alternative, so here it is.
Download ›
I recommend these Appearance settings in your prefs to keep things clean.

I've been using the Smooth theme made by David Ferguson for some time and realized i needed just that theme with somewhat inverted colours.
Credit goes to David.
Looks like this:
Download:
http://j.mp/18i5KN6

DigitalAttitude - minimal HUD
a dark and minimal HUD style Alfred v2 Theme
This simple theme is using only shades of black and white color for all background and text elements (20% - 85% opacity) and minimal border radius.
The text is rendered using Helvetica, and the theme is available in two versions, one with a border (25% opacity) and one without (more margin, more minimlizm).
Note: Try adding the blur hack, might look nice too! (the blur hack was not used/available while taking the screenshots)
Border-Version V2.1
Download: http://bit.ly/1161pbj
Non-Border-Version V2.2
Download: http://bit.ly/1162i3K
I hope you like this theme as much as I do,
Cheers,
Dan

Things I like:
light text on a dark background
easy to read font
a little bit of transparency
If you, too, like these things: http://d.pr/f/w1Wu
Thanks for posting all your themes and workflows. Alfred wouldn't be half as amazing without them.